The invention relates generally to bearings and more particularly to half bearings designed for use, although not exclusively, in the motor vehicle field. The half bearing of the present invention is a sleeve type half shell radial bearing having half thrust washers which provide for thrust or axial bearing capabilities.
In application, two semi-cylindrical shells, also called thin-wall inserts, are located in a support or housing through an interference fit. Most notably, half shell bearings are used in connecting rod and main bearings of gasoline and diesel engines.
Generally, flanged half shell bearings are of two types: the first type is a one piece variety in which the thrust washers or flanges are integrally formed with the curved edge of the shell itself, and a second type where the thrust washers are formed separate from a straight shell and are subsequently attached thereto. Each type has its own limitations and disadvantages.
The integral flanged half bearing entails a high cost of manufacture, complicated machining apparatus, and additional finishing steps. Moreover, the integral flanged half bearing operates at a higher temperature because of the reduced space between the flange and the engine block resulting from thermal expansion.
In the second type of flanged half shell bearings two general subclasses can be delineated. In the first subclass, the thrust washer is rigidly fixed to the shell by applying pressure axially to the washer and plastically deforming the shell. Again, manufacturing costs are relatively high and furthermore the rigidity of the connection between the thrust washers and the shell produce local tensions which eventually result in failure of the bearing. In the second subclass the thrust washers are free to move relative to the shell during use, thereby eliminating local tensions in the joining of the washer to the shell. Furthermore, this permits the washers to adjust themselves when positioned in the engine block and further decreases manufacturing costs. A particular problem with this type of flanged half bearing, illustrated in U.S. Pat. No. 4,533,261, is that the washer has a tendency to separate during normal handling and installation into the bearing housing.
Therefore, it is the object of the present invention to provide a flanged half bearing which does not separate when the half bearing is assembled into the engine block or housing.
It is another object of the present invention to provide a flanged half bearing where the washers are free to move axially when installed.
It is an additional object of the present invention to provide a flanged half bearing which does not restrain the free dimension of the straight shell to which it is attached.
In achieving the above objects the present invention includes a semi-cylindrical straight shell which is designed to be supported within a housing in an interference fit. Along the curved edges of the shell special cavities are symmetrically positioned. A thrust washer is attached to the shell along the curved edge. To facilitate this attachment, the thrust washer is provided with appendages corresponding in position to the cavities in the straight shell. The appendages and the cavities interfit and coact so as to retain the thrust washer in position on the shell. This engagement prevents separation of the washer from the shell while permitting fore and aft axial movement of the washer relative to the shell. The recessed portion of the straight shell is trapezoidal in shape with the base of the trapezoid being interiorly of the shell and having a dimension greater than the opening along the curved edge. The appendages of the washer are generally dovetailed and have a dimension which is slightly less than the opening along the curved edge but less than the dimension of the base of the recess portion. Upon being inserted into the cavities the washer is retainingly engaged with the straight shell by mechanically deforming or swaging the dovetailed appendage. Thus, the washer is inseparable from the shell and is free to move axially within the recessed portion thereof.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.